Efficacy of Ultraviolet Irradiation in the Inactivation of Waterborne Fungal Spores: Kinetics And Photoreactivation

In recent years, there has been extensive research on using ultraviolet (UV) disinfection, particularly concerning bacteria. However, there has been limited investigation into its effects on fungal strains. In this current study, we aimed to explore the behavior of two types of filamentous fungi when subjected to UV inactivation using a flow-through UV reactor (FTR-UV). The primary objective was to understand their inactivation and reactivation characteristics. To achieve this, we suspended spores of Aspergillus niger and Penicillium sp. in pH 7.20 buffered distilled water and allowed them to pass through the reactor at various UV doses. We then analyzed the impact on their inactivation and reactivation processes over 24 hours, both in the presence of light and under dark conditions. The two fungal species displayed differing responses to UV treatment and distinct abilities to repair damage. Utilizing the FTR-UV system in our experiments, we achieved an inactivation efficiency of up to 3 logarithmic units. This required doses of 376.9±61.7 and 271.6±29.9 mJ cm-2 for Aspergillus niger and Penicillium sp., respectively. The influence of the dark repair process was found to be minimal. Conversely, the photoreactivation process held some significance, particularly for Penicillium sp. Generally, Aspergillus niger exhibited greater resistance compared to Penicillium sp. However, the latter demonstrated a higher capacity for photoreactivation.